Heretofore, JP10-203338A (corresponding to US006113197A) proposes a vehicle brake control apparatus of a brake-by-wire type, which has four pumps respectively for four wheels of a vehicle. Two of the four pumps are located in a first conduit system and driven by a common motor, and the other two of the four pumps are located in a second conduit system and are driven by another common motor.
In the above-described brake-by-wire type brake control apparatus for a vehicle, each motor for actuating a control valve and the pump, which are provided at each conduit system, is basically driven by electric power supplied by a battery.
Due to some abnormality (e.g., a battery runs out of electric power), when the battery stops supplying electric power (hereinafter referred to as an electric power supply stopped situation), electric power charged in a capacitor, which is prepared as a backup battery, is used to drive each motor for actuating the control valve and the pump provided at each conduit system.
In this configuration, even when the electric power supplied by the battery is stopped (in the electric power supply stopped situation), a level of a pressure applied to each wheel cylinder (hereinbelow referred to as a W/C) by actuating the motor can be gradually changed so as to correspond to a level of a pressure set on the basis of a brake pedal operation by a driver.
However, in the electric power supply stopped situation, when the motor is driven in the same manner when the electric power is supplied by the battery (in a normal brake operation), because a large amount of electric power is consumed, a large size of the capacitor needs to be provided in order to store a large amount of electric power, otherwise an amount of electric power to be consumed in the electric power supply stopped situation needs to be reduced.
A need thus exists to provide a brake control apparatus for a vehicle having a capacitor that can apply a pressure to each W/C in an electric power supply stopped situation, wherein an amount of electric power to be consumed in an electric power supply stopped situation is set to be smaller than an amount of electric power to be consumed in a normal brake operation, in which the battery supplies electric power to the motor and the like.